Subject: + compilerh-dont-use-temporary-variable-in-__compiletime_assert.patch added to -mm tree
To: johannes.berg@xxxxxxxxx,daniel.santos@xxxxxxxxx,luciano.coelho@xxxxxxxxx,paulmck@xxxxxxxxxxxxxxxxxx,peterz@xxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 08 May 2014 13:35:06 -0700
The patch titled
Subject: compiler.h: don't use temporary variable in __compiletime_assert()
has been added to the -mm tree. Its filename is
compilerh-dont-use-temporary-variable-in-__compiletime_assert.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/compilerh-dont-use-temporary-variable-in-__compiletime_assert.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/compilerh-dont-use-temporary-variable-in-__compiletime_assert.patch
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From: Johannes Berg <johannes.berg@xxxxxxxxx>
Subject: compiler.h: don't use temporary variable in __compiletime_assert()
Usually, BUG_ON and friends aren't even evaluated in sparse, but recently
compiletime_assert_atomic_type() was added, and that now results in a
sparse warning every time it is used.
The reason turns out to be the temporary variable, after it sparse no
longer considers the value to be a constant, and results in a warning and
an error. The error is the more annoying part of this as it suppresses
any further warnings in the same file, hiding other problems.
Since this is all about compile time and the condition should be
side-effect free to start with, there's no downside (apart maybe from a
slight compilation time penalty?) to just duplicating it, leaving sparse
able to evaluate it at check time, getting rid of the warning and error.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Cc: Daniel Santos <daniel.santos@xxxxxxxxx>
Tested-by: Luciano Coelho <luciano.coelho@xxxxxxxxx>
Acked-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/compiler.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff -puN include/linux/compiler.h~compilerh-dont-use-temporary-variable-in-__compiletime_assert include/linux/compiler.h
--- a/include/linux/compiler.h~compilerh-dont-use-temporary-variable-in-__compiletime_assert
+++ a/include/linux/compiler.h
@@ -331,11 +331,10 @@ void ftrace_likely_update(struct ftrace_
#define __compiletime_assert(condition, msg, prefix, suffix) \
do { \
- bool __cond = !(condition); \
extern void prefix ## suffix(void) __compiletime_error(msg); \
- if (__cond) \
+ if (!(condition)) \
prefix ## suffix(); \
- __compiletime_error_fallback(__cond); \
+ __compiletime_error_fallback(!(condition)); \
} while (0)
#define _compiletime_assert(condition, msg, prefix, suffix) \
_
Patches currently in -mm which might be from johannes.berg@xxxxxxxxx are
compilerh-dont-use-temporary-variable-in-__compiletime_assert.patch
linux-next.patch
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